Method and apparatus for annealing



y 1937- R. M. PARSONS 2,079,334

METHOD AND APPARATUS FOR ANNEALING Filed March 2; 1935 Patented May d, 1937 warren stares r car es Ralph M. Parsona'Mount Vernon, Ohio, assigno'r to The Ralph M. Parsons Company, Mount Vernon, Ohio, a corporation of Delaware Application March 2, 1935, Serial N0. 8,993

dillaims.

This invention relates to annealing and more particularly to a process and apparatus for annealing large hollow articles such as pipes or vessels.

An object of this invention is to provide simplified and improved means for annealing large hollow articles.

Another object is to provide relatively cheap equipment for annealing such articles.

Another object is to provide for annealing such articles without use of a large heating chamber.

A more specific object is to provide an improved process for the manufacture of large pressure vessels for oil refineries.

Various other objects will be apparent as the nature of the invention is more fully disclosed.

In accordance with this invention the article to be annealed, which may comprise a heavy pres sure vessel of the type used in oil refineries, is heat insulated on the outside and hot gases are passed therethrough at a rate to heat the vessel .to the temperature desired for annealing. Thereafter the temperature and flow of the gases are controlled so as to maintain the temperature time'characteristics required for annealing. The hot gases may comprise air, furnace gases, superheated steam, hot'oil vapors or the like, depending upon the availability. The vessel may K be insulated by being embedded in the earth or in a pit or receiver containing any natural insulating material'such as earth, clay, Zonolite, mica, limestone, or the like.

Various novel features which are believed to be characteristic of this invention will be more particular-ly pointed out in the claims appended hereto, but the invention itself may be better understood by referring to the following description taken in connection with the accompanying drawing in. which one embodiment thereof has been set forth for purposes of illustration.

In the drawing, the figure is a diagrammatic representation of one means forcarrying out the invention.

Referring to the drawing more in detail the invention is shown as applied to the annealing of a large pressure vessel 50, such as a reaction chamber for an oil cracking plant. Such a vessel may be fabricated by spot welding which produces local regions of varying stress which must be relieved before the vessel is placed in use. Stress relieving requires a temperature-time characteristic well known in the annealing art and consisting in general of heating the article to a predetermined temperature, for example l600 E. and cooling through a. given temperature range at a. definite rate. In some instances reheating and recooling may be required. The present invention provides for obtaining whatever temperature-time characteristics may be required in accordance with general annealing practice and is not to be limited toany specific example thereof.

A reaction chamber may be, for example,forty feet long and five feet in diameter. Hence, if the annealing were to be accomplished in a furnace or heating chamber, a large and expensive construction would be required. In accordance with the present invention however the necessity for such a furnace is eliminated.

More specifically, the vessel I0 is heat insulated on the outside by means of an insulating ma terial i i such as, earth, clay, Zonolite, limestone, mica or the like, preferably by a material that is locally available and may be cheaply obtained. In parts of Montana, for example, Zonolite is readily obtained and may be conveniently used for this purpose. This material has a mica base and may be pumped or transported as a.

flaky mass. A receiver, such as a pit l2, may V be partly filled with this materiaL the vessel I!) placed therein and further quantities of the material may be added until the outer surface of the vessel It is covered to the desired extent. If no special insulating material is locally available the vessel in to be annealed may be buried in the ground. The efiiciency of the heat insulation'is not of great importance as only a few articles will be treated at any one plant and fuel will be a relatively small item.

Pipes l4 and [5 may be connected to the two ends of the vessel in, as by couplings is which may be secured to the vessel as by bolts IT and may be attached to the pipes i l and I5 by flanges i9 and bolts 20. The pipe it may lead to a source of hot gases such as a furnace 25 having a burner 26 provided with a fuel supply line 21 and an air supply line 28. The furnace may be of any convenient construction. If a furnace is included in the plant equipment, such for example as the cracking furnace of an oil cracking plant, the same may be used for this purpose. If a source of superheated steam is available the steam may be supplied to the pipe it in the same manner.

In the embodiment disclosed the pipe i l constitutes the exhaust duct for the combustion gases from the furnace 25. The pipe it may constitute a discharge means for the gases after they have served, their purpose in heating the vessel it.

In order to obtain a more efiicient heat transfer from the gases to the vessel 10 recirculation 50 ing bent pipes of large dimensions which would a" a far:

may be employed. For this purpose a pipe 35 is provided which interconnects the pipes M and i at points near the vessel it. The pipe 35 may contain a source of pressure such as a blower 35 adapted to produce circulation therein in a direction from the pipe i5 and toward the pipe it. The pipe'3ll may join the pipe it at an angle so as to vdischarge'gases toward the vessel i0 whereby circulation of gases from the furnace 25 in the vessel it is induced in the pipe M. A baflie 32 may assist inobtalning this circulation. The relative quantity of gases recirculated through the pipe 30 may be controlled by a damper 33 located therein, preferably ahead of the blower 3i. The flowof gases from the furnace 25 may be controlled by a damper 36 in the pipe M. A suitable temperature indicator such as a pyrometer 35 may be located in the pipe it at a point near the vessel '50 to show the temperature obtaining in the vessel.

In the operation of this invention the vessel It is placed in the bed of insulating material ii in a pit i2 or the like, pipes Mand I5 are connected thereto, and the burner 26 is regulated to produce the desired combustion in the furnace 25. The hot gases of combustion pass from the furnace 25, through the pipe 16 to the vessel ill, thence out through the pipe i5. Recirculation is obtained by regulating the blower3i and the damper 33 in the pipe3li. By suitable control of the rate of combustion, the recirculation and the flow of gases from the furnace to the vessel in, the temperature may be raised to any value desired. Thereafter the. rate of cooling may be controlled in a similar manner. Obviously if no heat is required during certain coolingstages, the flow of gases from the furnace may be entirely interrupted.

This process provides economical means for annealing large, articles at the plant. This renders it possible to construct such articles in the field and anneal them as required, as distinguished from manufacturing the articles at a point equipped with large furnaces and other annealing equipment.

The vessel I0 is shown by way of illustration only. The method may be employed for pipes, and other hollow articles with equal advantage. The invention is particularly useful for anneale require a large heating chamber if the pipe were to be annealed by heat externally applied.

It is obvious that recirculation may be omitted if the proper temperatures are otherwise ob- 5 tained. The gases employed should be such as not to attack the metal of the vessel. In some cases air may be employed, or in the case of pipes a liquid such as oil may prove satisfactory. superheated steam'may be used when available.

In general, any fluid may be used which is capable of transferring its heat to the walls of the article.

Certain specific terms have been used herein for convenience but they are to be interpreted as broadly as the art will permit. Although a specific embodiment of the invention has been set forth, various changes, modifications and adaptations will readily occur to a person skilled in the art. The invention is to be limited only. in accordance with the following claims when interpreted in view of the prior art.

What is claimed is:

1. Apparatus of the class described comprising a source of hot gases, a pipe adapted to lead said gases from said source to an article to be annealed, means to control the flow of said gases in said pipe, a second pipe adapted to discharge hot gases that have passed through said article, a third pipeinterconnecting said first pipes, blower means therein to cause recirculation of gases through said article, means to control the quantities of gases thus recirculated, and means whereby flow of said recirculated gases induces circulation of gases from said source to said article.

2. The process of annealing a large hollow article without using an annealing oven which comprises sealing the article against escape of gases therefrom, heat insulating the outside thereof, introducing a hot fluid into said article;

causing the fluid to pass entirely through said comprises sealing the article against escape of- V gases therefrom, heat insulating the. outside thereof, introducing a hot fluid into said article, 4

causing the fluid to pass entirely through said article for uniformly heating the walls thereof and then to be discharged therefrom, recirculating controlled portions of said fluid to increase temperature-time characteristic required for an nealing by controlling the temperature and rate of flow of said fluid.

4. The process of annealing a large hollowthe heat transfer therefrom and obtaining the article without using an annealing oven which through said article for uniformly heating the walls thereof and then to be discharged therefrom, and obtaining the temperature-time characteristic required for annealing by controlling the temperature and rate of flow of said fluid.

RALPH M. PARSONS. 

